38 MINERALS, ROCKS, AND GEOLOGY. 



fastened together by lime or by iron. (Keep for a week or more a rusty 

 piece of iron in damp sand.) Study sandstone — first, coarse-grained sand- 

 stone, showing that it is made of pieces of quartz, and later finer grained 

 stone. Show, by experiment, how water stratifies materials or arranges 

 them in layers, and touch on the story told by the stratification or layers of 

 sandstone. , 



Soil-making. — Collect "rotten" limestone and sandstone, showing that 

 they do break down into soil. Call attention to the cracks in rocks into 

 which water soaks. Show, by experiment, how water expands when 

 freezing and how the freezing of water breaks the rocks, and tell how the 

 roots aid the water. Study in May the decaying leaves in gutters, and 

 the different stages in the change from leaf to soil (October, November, 

 April, and May). 



Field Lessons. — Collect rocks in fall. Study leaves and rock disinte- 

 gration in spring. 



THIRD YEAR. 



Object of Work. — As in second year, but with more attention to struc- 

 ture and distinguishing characteristics. 



Limestone. — Review work of previous year, leading to story of forma- 

 tion of limestone from corals and shells (see animal study). (November and 

 December.) 



Sandstone. — Quartz, sand, and sandstone, as in second year, but with 

 more varieties, including fine-grained sandstones and shales and several 

 varieties of quartz. Study their story carefully and emphasize distinctive 

 properties (January). 



Granite. — Feldspar, hornblende, and mica, their distinctive properties 

 and uses ; their combinations, with quartz, into granite. Binary and tern- 

 ary granite. Uses of granite (January). 



Soil-making. — As in second year, but more carefully. 



Work of Water — Formation of Valleys. — Study what the water does 

 with the soil — how it wears it away, carries it along and deposits it. 

 Study, after a rainstorm, formation of rills and gullies, and the trans- 

 portation and deposit of material (October, November, April, and May). 



Field Lessons. — Collection of rocks (October and November). Forma- 

 tion of soil and work of water (October, November, April, and May). 



FOURTH YEAR. 



Special Object. — A more thorough study of common earth-forming min- 

 erals, their occurrence, formation, properties, common varieties, and uses. 



Limestone. — Emphasize the study of fossils and their story, the varie- 

 ties of limestone (calcite, chalk, tufa, marble) and their formation, dis- 

 tinctive characteristics and uses, the manufacture and uses of lime (De- 

 cember). 



Sandstone and Stratified iJocfcs.— Varieties and uses of sandstone. 

 Stratified rocks, their characteristics, occurrence, and the story of their 

 formation (December and January). 



